Paste- or film-like anisotropic conductive materials are utilized when mounting an IC chip on a wiring board. For example, FIG. 1 illustrates an IC chip 10 having bumps (including outer bumps 1a and inner bumps 1b) arranged in a staggered manner on at least a part of a peripheral portion of the back face of the IC chip. As illustrated in FIG. 2, an anisotropic conductive material is utilized when connecting the IC chip 10 to a wiring board 21, which has wiring terminals 20 corresponding to these outer bumps 1a and inner bumps 1b, via an anisotropic conductive material 22 by the application of heat and pressure by a heating and pressurizing head 23. Furthermore, FIG. 3 illustrates a flexible wire 33 on which linear electrodes 31 arranged in parallel on one face of a polyimide sheet 30 are exposed from a cover lay film 32. As illustrated in FIG. 4, an anisotropic conductive material is also utilized when connecting the flexible wire 33 to a glass substrate 35 for a display panel, which has wiring terminals 34 corresponding to the electrodes 31, via an anisotropic conductive material 36 by the application of heat and pressure by a heating and pressurizing head 37.
However, to reliably connect an electronic part such as an IC chip having bumps or connecting electrodes with a fine pitch to a wiring circuit board via an anisotropic conductive material, the conductive particles have to be made sufficiently available in a compression-bonding region, and excess binder has to be removed from the compression-bonding region.
Previously, to handle such demands, an anisotropic conductive material has been proposed in which a minimum melt viscosity is adjusted to be in a range of from 1×106 to 1×109 mPa·s (Patent Document 1, Claim 5 and paragraph [0031]).    [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-340614